The unusual and dynamic character of PX-DNA.
Bottom Line: Some of the structural features of the molecule have been noted previously, but the structure requires further characterization.Here, we report atomic force microscopic characterization of PX molecules that contain periodically placed biotin groups, enabling the molecule to be labeled by streptavidin molecules at these sites.In comparison with conventional double stranded DNA and with antiparallel DNA double crossover molecules, it is clear that PX-DNA is a more dynamic structure.
Affiliation: Department of Chemistry, New York University, New York, NY 10003, USA.Show MeSH
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Mentions: The first structure we examined was a DNA duplex, expected to assume the B-conformation. For satisfactory visualization resolution, the length of the duplex is 270 bp, roughly 92 nm (12). One strand is labeled with five biotin-streptavidin conjugates with alternate separations of 52 and 53 nt pairs between any two adjacent labels, so as to have all the labels positioned on the same side of the duplex (Figure 2A). The sample was then examined by AFM, and as shown in Figure 2A, the corresponding linear conformation was observed clearly with a frequency of 91%. Zoomed-out AFM images of relevant species are shown in Supplementary Figure S2 to confirm frequencies of occurrence.
Affiliation: Department of Chemistry, New York University, New York, NY 10003, USA.